Stage I Melanoma

Patients with stage I melanoma have cancer that is found in the outer layer of the skin (epidermis) and/or the upper part of the inner layer of skin (dermis), but has not spread to lymph nodes, and the primary melanoma is less than 2 millimeters (1/16 of an inch) thick.

The most important initial feature that is obtained from biopsy at the time that the melanoma is diagnosed is the thickness of the melanoma (Breslow thickness, measured in millimeters). A pathologist determines this thickness by examining the melanoma under a microscope and measuring the lesion from the top to the bottom. Based on the thickness of the tumor, melanoma is divided into 3 general categories:

Thin melanomas, which are less than or equal to 1 mm in thickness

Intermediate thickness melanomas, which are between 1 mm to 4 mm

Thick melanomas, which are greater than 4 mm

The thicker a melanoma is determined to be at the time of diagnosis, the greater the chance that it has spread. In general, melanoma spreads to the lymph nodes in the region of the primary cancer first.

In addition to thickness, there are other features that can determine the “aggressiveness” or likelihood that the tumor has spread.1,2

Microscopic absence of the continuous epidermis in the tissue overlying the melanoma, which is referred to as ulceration.

Penetration to Clark Level IV (invades deeper through the dermis, but still contained completely within the skin).

Surgical Treatment of Stage I Melanoma

The standard treatment of stage I melanoma is surgical removal with pathologically confirmed negative margins. Efforts been made to reduce the amount of normal skin removed without compromising the cure rate achieved with surgery. A melanoma greater than 1 millimeter appears to require a greater surgical margin to reduce the rate of recurrence at the site of origin. Most surgeons recommend a surgical margin of 2 centimeters (almost an inch) surrounding the entire cancer for melanomas greater than 1 mm. The need for skin grafting occurs in approximately 10% of patients. Surgical margins greater than 2 cm are no more effective and require skin grafting in a higher fraction of patients (up to 50%).

Evaluation of the regional lymph nodes by performing a sentinel lymph node biopsy (SLNB) as a staging procedure for patients with a primary melanoma greater than 1 mm is recommended. SLNB should also be considered in patients with thin melanomas (< 1 mm) and adverse prognostic factors, such as vertical growth phase, Clark Level IV, regression, and ulceration.3,4

The surgical treatment of stage I melanoma typically involves a single procedure in which a local excision of the cancer is performed as well as a SLNB. Approximately 15% of patients undergoing SLNB have a positive SLN (pathologically stage III). Ninety-five percent of patients with a confirmed negative “sentinel node” are free of cancer and require no additional treatment.5

Over 90% of patients with melanomas of less than 1 mm are cured following surgical removal of the melanoma. In one clinical study of patients treated at the Mayo Clinic, the 5-year survival rate for stage 1 melanoma of 0.75 mm or less was 98%.

Questions to Ask your Physician

Patients with melanoma of less than 1 millimeter should ask their physicians whether or not their melanoma demonstrated any evidence of ulceration, vertical growth phase, regression, or whether it is Clark level IV. Patients should also inquire about the treatment results achieved at the cancer center or institution where they are considering treatment.